Howdy Cegorach,

The existing MTW British Isles map divisions aren't that good for the mediaeval period, and are woefully inadequate for the renaissance. I appreciate that many of these concerns would be addressed in your possible English Civil War mod, but if you're still taking input for the main P&MTW map, here's a precis:

Scotland
At least have it split in two - The Highlands and The Lowlands. The capital for The Highlands would be problematic, but Inverness might just do, or Inverary, or Blair Atholl, and would be represented by a keep. The Lowland's capital would be Edinburgh, with a castle. In your early and middle periods, both would be simply in Scotland, but with a higher risk of rebellion in the Highlands. In your late period it should change: the Highland's leader could be called the Earl of Montrose, and he'd be Royalist, with many of his units actually Irish, the rest being highlanders. The Lowlands late period leader could be the Marquess of Argyll (but with Sir David Leslie as their best general, equal in skill to Cromwell), and they would be the Covenanters and either replace later period Scotland as a nation or be a neutral rebel territory (having been allied to the Roundheads in the first civil war, but against them in the second).

Engalnd and Wales
Even more difficult. London was never the capital of Wessex nor did Wessex extend across all southern England. Wales has been fully subjugated to England and as a nation plays no separate part. Here is breakdown by province:

Wales is administered from Ludlow (in Shropshire, England) and thus its boundary should be extended to include that county (basically, move the westernmost 20% of Mercia into Wales and call it "Wales and the Marches"). Represent Ludlow by at least a castle.

London (citadel) the capital of a new region called "The Home Counties", that is basically the southeast of England (i.e. taken from the eastern half of Wessex and southeastern corner of Mercia).

The remaining western half of Wessex should have Bristol as its castle with ring wall capital (representing second British city to London), with Bristol or Plymouth as its main port, but the province to be called "The West Country".

Mercia retained but now smaller, capital Nottingham (with a castle).

Northubria might be better called "Northern England" with York its castle capital, replacing the current Northumbria (if there was space it would better to have both Northumbria and Yorkshire as provinces).

Ireland
At least two provinces (preferably four if there were space, which I doubt). To overly simplify: The middle of the eastern half (the region around Dublin) could be called "Leinster" or "The Boil", and be an English then Roundhead province, but one which could easily rebel. The rest still called "Ireland" but really this was (at least) Munster, Connaught and Tyrone - but I doubt there'd be space for this on the P&M Europe map.

So all that would mean finding at least 3 more provinces for the British Isles. This would still ignore the existence of East Anglia as a possible province (with Norwich as its capital), but there wouldn't be space for that as well as Mercia and the Home Counties on the P&M Europe scale map. If you can't find 3 more province slots, at least rename Wessex to "Southern England", and do the Northumbia name changes. Again, all this still a gross simplification of reality.